#14591: cosh integral incorrect because of abs_integrate
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Reporter: kcrisman | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-6.3
Component: calculus | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by pbruin):
Replying to [comment:8 kcrisman]:
> As Thierry pointed out on the ask.sagemath question.
Yes, I just wanted to give a clear reason here why the answer couldn't
possibly be right.
> So, does #13973 fix this or not?
No, it doesn't. I have been doing some debugging of the Maxima command
{{{
trigsimp(integrate(sqrt(4 - cosh(x)^2),x));
}}}
which returns `cosh(x)` when executed after loading `abs_integrate`. It
seems that the problem arises in `ratsubst`, when substituting `1 +
sinh(x)^2` for `cosh(x)^2`. What makes it more tricky is that calling
`ratsubst` directly with the same arguments gives a correct answer.
Possibly some flag is set at some intermediate point that triggers the
bug.
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Ticket URL: <http://trac.sagemath.org/ticket/14591#comment:9>
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